Stabilizing solution of tetra-alkyl lead compounds



Patente ea. 1, 1942 STABHJZING SOLUTION OF TETRA-ALKYL LEAD COMPOUNDS Pennsylvania No Drawing.

Original application January 31,

,7 1940,,Serial No. 316,686. Divided and this application March 31, 1942, Serial No. 437,087

5 Claims.

This invention relates to stabilizing solutions of tetra-alkyl lead compounds; and it comprises a method of stabilizing said solutions particularly ethyl gasoline wherein the development of a hazy appearance is inhibited by adding to such solutions small quantities of benzal-xylidine; all as more fully hereinafter set forth and as claimed.

This application is a division of our copending application, Serial No. 316,686 as filed January 31, 1940.

It is customary in the production of so-called ethyl gasoline to add to a good grade of gaso-. line a small amount of a tetra-alkyl .lead compound, usually tetra-ethyl lead to reduce the tendency of the gasoline to cause knocking in high compression gasoline engines. The amount of tetra-alkyl lead compound added. to a gasoline depends upon the nature of the gasoline and the desired anti-knock rating. Tetra-ethyl lead is customarily added to the gasoline in the form of a concentrate called ethyl fluid which is a solution containing a mixture of tetra-ethyl lead, alkyl (ii-halide (e. g. ethyl di-bromide or'ethyl di-chloride or both) and a small amount of a dye to impart a distinctive color to the gasoline. The function of the alkyl di-halides is to limit the formation of lead oxide from tetra-alkyl lead in the cylinders of the engine by forming volatile halides of lead which are carried out in the exhaust. The ethyl fluid is added to the gasofrom disadvantage. For one thing, leaded gas0-- line tends to develop a hazy appearance upon standing, particularly in the presence of strong sunlight.- For example, in direct sunlight in the summer time, ethyl gasoline may develop a perceptible haziness after an hour or two of exposure, and longer periods of exposure result in a very marked haziness and precipitation occurs. This phenomenon is also sometimes observed in the ethyl fluid itself.

The formation of haze in gasoline is objectiona clear product; customers prefer a product which is crystal clear. A further and perhaps more important objection is that a reduction in the octane rating of gasoline is frequently associated with haze formation. Also damage is likely to occur in the fuel lines and carburetor. The development of haze in ethyl fluid itself is also objectionable, because when a hazy ethyl fluid is blended with gasoline to form ethyl gasoline, the haze is introduced into the fuel with all its attendant disadvantages.

An object achieved by this invention is to provide solutions of tetra-alkyl lead compounds, such as ethyl fluid and ethyl gasoline which are stabilized against haze formation.

We have found that haze formation in solutions of tetra-alkyl lead compounds, such as ethyl fluid and ethyl gasoline, can be very materially reduced by incorporating in such solutions small quantities, proportions on the amount of tetraalkyl lead compound in solution, of benzal-xylidine having the formula wherein R1 is a xylyl group and R2 is a phenyl group.

Benzal-xylidine may be added with advantage to solutions generally of tetra-alkyl lead compounds and more particularly to all types of leaded gasoline. A manner of incorporating the henzal-xylidine in solutions of tetra-alkyl lead compound is not critical. It may be incorporated in the ethyl fluid at any stage during the preparation thereof, or it may be incorporated in the gasoline prior to the addition of ethyl fluid along with the ethyl fluid or subsequent to blending the ethyl fluid with the gasoline.

Even very small amounts of benzal-xylidine are sufiicient to exert a substantial stabilizing effect against light in fluids containing tetra-alkyl lead compounds. In general with higher percentages of tetra-alkyl lead compounds, higher amounts of benzal-xylidine are required. Within the range of about 0.01 to aboutl per cent by weight of tetra-ethyl lead in gasoline, a substantial stabilizing effect is exerted by from about 3 to about 120 pounds of benzal-xylidine per thousand barrels of gasoline. Within the range from about 0.02 to about 0.40 per cent by weight of tetra-ethyl lead in solution, which represents a commercial range, it is advantageous to employ from about 10 to about 40 pounds of benzal-xylidine per thousand barrels of gasoline. Such u because the gasoline is not as marketable a 55 amounts will exert a marked stabilizing effect against light and will produce a commercial ethyl gasoline which is satisfactorily stable to light under the usual conditions of exposure.

. xylidine incorporated in the ethyl fluid is generally somewhat greater than is required for stabilization of the concentrate so that by the addition of the usual small amount of ethyl fluid to the gasoline a suitable stabilizing amount of benzal-xylidine will be incorporated in the gasoline. Generally from 1 to per cent by weight,

from compounds available on the market at a relatively low cost, and its mode of preparation is simple and inexpensive.

based on tetra-ethyl lead, of benzal-xylidine very satisfactorily stabilizes commercial tetra-ethyl lead concentrates, such as ethyl fluid and on adding the stabilized concentrate to gasoline to produce ethyl gasoline, a satisfactorily stabilized ethyl gasoline is obtained.

In general, we have found that benzal-xylidine is a more potent stabilizer against haze formation to its stabilizing properties has other prop erties which particularly recommend it for this use. It does not adversely affect the oxygen stability of the gasoline. Samples of cracked ethyl gasoline containing benzal-xylidine have been.

aged and tested for oxygen stability and by the copper dish method for gum formation. The presence of the benzal-xylidine did not promote either oxygen instability or gum formation. It is non-corrosive to common'packaging materials such as steel, zinc, copper and tin and is compatible with the dyes commonly used in ethyl gasoline to give it a distinctive appearance. It is sufliciently soluble in gasoline to accomplish the intended stabilization. Furthermore it is insoluble in water, which is a distinct advantage because contact with water will not result in I leaching the stabilizer out of the gasoline. Con

tinued storage of gasoline containing benzalxylidine does not affect its stabilizing properties.

. Also benzal-xylidine can be readily prepared The following specific examples will serve to H- lustrate the excellent haze inhibiting properties of benzal-xylldine.

Eazample.--Ethyl gasoline containing 0.1 per cent by weight of tetra-ethyl lead (added in the form of ethyl fuel comprising tetra-ethyl lead, ethylene dibromide and a dye) was treated with benzal-3,5-xylidine in the proportion of 20 pounds of the latter per thousand barrels of gasoline.' The resulting solution was exposed for-five hours to sunlight and the appearance of the gasoline was noted. At the endof the 5 hours exposure there was a small degree of haziness but a great improvement over the appearance of the v same gasoline containing no benzal-xylidine. This was considered a fair stabilization.

The benzal-3,5-xylidine employed in the above example has the following formula and is a most efiective stabilizer for the present purposes. In addition to being a most potent stabilizer it can be easily incorporated in the leaded gasoline; it being a liquid readily soluble in gasoline.

While our invention has been described herein with reference to certain specific embodiments at pecific examples thereof, we do not intend that our invention shall be limited'to such embodiments and examples except as hereinafter defined in the appended claims.

What we claim is:

1. A method of producing a. light-stable solution of a tetra-alkyl lead compound which comprises incorporating in said solution benzal-xylidine-in amount suflicient to inhibit the forma-.

tion of haze in said solution.

2. The method of claim 1 whenein the tetraalkyl lead compound is tetra-ethyl lead.

3. The method of claim 1 wherein the benzalzylidine compound i benzal-3,5-xylidine.

4. A method of producing a light-stable, antiknock motor fuel containing a tetra-alkyl lead compound which comprises incorporating in said motor fuel benzal-3,5-xylidine in an amount corresponding to 0.01 to 1.0 per cent by weight of the tetra-alkyl lead compound.

. 5. As an improved anti-knock motor fuel stable to light, a gasoline containing 0.02 to 0.4 per cent by weight of tetra-ethyl. lead and about 10 to 40 pounds of benzal-3,5-xylidine per 1,000 barrels of gasoline.

TROY LEE CAN'I'RELL. CARLTON LOUIS SUPLEE. 

